Fig. 3

a Comparison of observed Bouguer anomalies projected on the line X–X′ across the TNF (gray circles), the smoothed and resampled ones (open circles), and those calculated from the optimum density structure using the 2D Talwani’s method (red line). Data in the gray areas are not used for the calculation. b Schematic view of the model parameters of the 2D density structure. A triangle shows the location of the surface trace of the TNF (at distance = 0). A dark gray layer near the surface represents the sediment layer with 20 m thickness